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https://issues.apache.org/jira/browse/CALCITE-2041?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16252187#comment-16252187
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Jesus Camacho Rodriguez commented on CALCITE-2041:
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[~julianhyde], we have been trying to create tests for this issue
(ReduceExpressionsRule#FILTER_INSTANCE is disabled by default so we tried to
use RelOptRulesTest), but we could not come up with same plan as in Hive. Do
you have any other suggestions? [~bslim] has been testing the rule in Hive with
the change his proposed change (HIVE-17871) and everything is working as
expected and without issues, so I would like to check in the patch if possible.
To be clear, the proposed change is quite straightforward: it exposes a flag to
match to indicate whether reduce expressions should match nullability or not
when expressions are simplified (by default it is _true_, so current behavior
is preserved).
> Adding the ability to turn off nullability matching for ReduceExpressionsRule
> -----------------------------------------------------------------------------
>
> Key: CALCITE-2041
> URL: https://issues.apache.org/jira/browse/CALCITE-2041
> Project: Calcite
> Issue Type: Bug
> Reporter: slim bouguerra
> Assignee: Julian Hyde
>
> In some cases, the user needs to select whether or not to add casts that
> match nullability.
> One of the motivations behind this is to avoid unnecessary casts like the
> following example.
> original filter
> {code}
> OR(AND(>=($0, CAST(_UTF-16LE'2010-01-01 00:00:00
> UTC'):TIMESTAMP_WITH_LOCAL_TIME_ZONE(15)), <=($0, CAST(_UTF-16LE'2012-03-01
> 00:00:00 UTC'):TIMESTAMP_WITH_LOCAL_TIME_ZONE(15))))
> {code}
> the optimized expression with matching nullability
> {code}
> OR(AND(CAST(>=($0, 2010-01-01 00:00:00)):BOOLEAN, CAST(<=($0, 2012-03-01
> 00:00:00)):BOOLEAN))
> {code}
> As you can see this extra cast gets into the way of following plan
> optimization steps.
> The desired expression can be obtained by turning off the nullability
> matching.
> {code}
> OR(AND(>=($0, 2010-01-01 00:00:00), <=($0, 2012-03-01 00:00:00)))
> {code}
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